There is broad consensus today that personality traits are best described by the "Big Five": Extraversion, agreeableness, conscientiousness, emotional stability, and openness to experience. Each of these broad measures can be broken down into smaller ones, but in general, this taxonomy appears to take in most of what we think of as personhood. When you think of someone as "steady" or "flaky" or "gloomy" or "daring," what you’re really doing is unconsciously taking a measure of these five traits and crunching them together.

So what makes a healthy personality? Psychologists have been studying this important question, and at least two of these five traits appear to be directly related to physical well being and longevity: Emotional stability and conscientiousness. More to the point, wellness is linked to changes in these traits over time.

Consider emotional stability. Or, rather, it’s polar opposite, which psychologists call neuroticism. Neuroticism is the tendency toward hand wringing and negative thinking. People with a heavy dose of neuroticism do not handle stress well, and are often anxious and moody. Such negativity has been linked to increased mortality in a number of studies, but for Purdue University psychologist Daniel Mroczek this finding raised as many questions as it answered. Does it follow that this inherited trait is a death sentence? Or can people with this propensity change their destiny?

Mroczek decided to explore this idea. Using a standard measure of neuroticism, he tracked more than 1600 men over 12 years, recording not only how neurotic they were at the start but also whether they got more or less neurotic over time. He also looked at mortality risk for these same men over an 18-year span. As reported in the May issue of Psychological Science, those who increased over time in neuroticism was a ticket to an early grave. In other words, these men—all middle age or older to begin with—did not grow old gracefully. They likely got more and more stressed, worried or fretful, and this downward spiral increased their risk for dying, mostly from cancer and heart disease.

The good news is that men with a fretful temperament, if they managed for whatever reason to calm down a bit over time, had survival rates similar to those of emotionally stable men.